Treatment effects of the twin block appliance: a cephalometric study.

A clinical study was undertaken to investigate the treatment effects of a modified Twin Block appliance. Pretreatment and posttreatment cephalometric records of 28 consecutively treated patients with Class II malocclusions were evaluated and compared with an age- and sex-matched sample of untreated Class II control subjects. The treatment group was considered to have severe skeletal Class II malocclusions and was treated using only the Twin Block appliance. Results indicated that mandibular growth in the treatment group was on average 4.2 mm greater than in the control group over the 14-month treatment period. In addition, some dentoalveolar effects in both arches contributed to the overjet correction. No statistically significant increase in the SN-mandibular plane angle occurred during treatment and, in general, the magnitude and direction of the skeletal changes were found to be quite favorable.